In a repeating firearm it is necessary to provide means for storing cartridges, means for successively delivering them to the barrel, means for firing a cartridge in the barrel, and means for ejecting the spent cartridge. Many systems have been proposed and placed into use for performing these functions, but difficulties have been encountered in providing systems which are strong enough to resist the recoil of a powerful cartridge upon firing, since relatively small lugs are often relied upon to lock a bolt against the end of a barrel. In addition, many systems are complex and prone to jamming.
Some have proposed utilizing vertically sliding blocks or bolts, but such systems have not come into widespread use. Among these are those shown in U.S. Pat. Nos. 2,402,159 to Grill; 290,737 to Brown; 3,733,729 to Baker; and 3,495,349 to Thompson.